Shading issue with normal map

Hello everybody!

I was trying to shade this tire model in B4W. This is the node tree and how the model looks in Blender's viewport. Everything's fine.



And this is how it looks like when I run the blend4web Preview:



As you see there's a weird shading issue going on and I can't figure out why. I have already thought of several common pitfalls but found no working solution so far.
Can anybody help me? Thanks in advance!

Hi! Can you attache the blend file?

Yes, of course!

Forum_test.blend

Ah, sorry, the map wasn't packed. Here it is with packed textures:

Forum_test.blend

As you see there's a weird shading issue going on and I can't figure out why. I have already thought of several common pitfalls but found no working solution so far.
Can anybody help me? Thanks in advance!

Please make sure you've selected Non-Color space for the normal map image

I did. :-(

Ah, sorry, the map wasn't packed. Here it is with packed textures:

Forum_test.blend

You have an Hemi as light source it has a different implementation of specular in Blender and Blend4Web, try to use sun or any other and you'll get the same result.

Sorry, but that doesn't work either. I tried sun, point and spot, but it didn't change anything.

I did. :-(

In the file that you've attached color space for normal map image is not Non-Color

Changing highlighted value to Non-Color works for me.
If it really doesn't solve your issue please provide info about your system and blend4web version

OK, seems I use an outdated blend4web version (because that would be the only explanation why it works for you). I'll update and check again. Thank you!